Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-05-23
2004-06-01
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S112000, C310S156010
Reexamination Certificate
active
06744164
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor mainly for use with the electric vehicle or the like, an electric vehicle and a hybrid electric vehicle.
2. Description of the Related Art
Conventionally, an internal combustion engine has generally been used as a prime mover for an automobile.
In recent years, air pollution, global atmospheric warming-up or the like have become an issue, and in terms of protection of global environment, development of an electric vehicle using an electric motor as its prime mover has been proceeding.
Among others, it is an electric vehicle such as a fuel-cell electric vehicle using a fuel cell as power supply and a hybrid electric vehicle using a battery as power supply that have been in the limelight for the last several years.
In the case of the former fuel-cell electric vehicle, since a motor is used for the power, there is no exhaust gas at all, both vibration and noise are exceedingly low as compared with the internal combustion engine, and in addition, a fuel cell having greater energy density than an ordinary battery is used as power supply, and therefore, there is the advantage that the fuel-cell electric vehicle has much longer travel distance per charging.
Also, as the latter hybrid electric vehicle, there has been developed a parallel hybrid electric vehicle or the like which directly drives drive wheels by combining a conventional engine, which is easy to supply fuel, with a motor, which is clean as energy, to use these power (Japanese Patent Laid-Open No. 59-63910 and U.S. Pat. No. 4,533,011).
In this respect, the entire disclosure of the Japanese Patent Laid-Open No. 59-63910 and U.S. Pat. No. 4,533,011 is incorporated herein by reference in its entirety.
As the structure of such a hybrid electric vehicle, there has generally been known a vehicle in which driving by the motor or driving by the engine is appropriately switched in accordance with various conditions such as traveling speed and travel area through the use of connection such as clutch to transmit driving forces (mechanical power) of those engine and motor to the drive wheels through power transmitting means such as transmission for traveling.
Also, in this sort of hybrid electric vehicle, the motor is caused to generate a driving force during, for example, acceleration of the vehicle, and it is added to an output from the engine to transmit to the drive wheels, whereby while acceleration performance to be required of the vehicle is being secured, the engine's output is restrained, and reduction in fuel consumption and exhaust gas of the engine is planned.
Further, in the case of the hybrid electric vehicle, during, for example, deceleration of the vehicle, it is common practice to drive the motor as a generator for regenerative power generation by means of kinetic energy of the vehicle to be transmitted to the motor from the drive wheels through the power transmitting means, and to recover the regenerative power generation out put thus obtained for accumulation. Concretely, the recovered power is directly accumulated in electric energy storing means itself such as the power supply battery for the motor.
In contrast, a method and structure for recovering and accumulating regenerative power in the case of the fuel-cell automobile are different from the case of the hybrid electric vehicle.
Concretely, the fuel cell itself is provided with an auxiliary cell or the like for exclusive use in storing regenerative power because it is not capable of directly receiving any regenerative power structurally.
As a motor for power for such a fuel-cell automobile, however, a small-sized, high-output, high-efficiency interior permanent magnet motor is optimum, but when a rotor of the motor is rotating during traveling or during regenerative control, a permanent magnet rotor generates generated voltage. This generated voltage is applied to the power supply (fuel cell) through an invertor as reverse generated voltage. Since the fuel cell is vulnerable to overvoltage and is not capable of directly receiving any regenerative power structurally as described above, an auxiliary cell or the like are connected to return the regenerative power (see FIG.
4
).
In this respect, it is possible in principle to prevent the reverse generated voltage from the motor from being applied to the fuel cell by separately providing switching means between the motor and the fuel cell to electrically separate both, but here, the description has been made of a general case where such switching means is not provided.
Therefore, the reverse generated voltage is also applied to the fuel cell during ordinary traveling or during regenerative control. However, since the motor does not rotate at much high speed during ordinary traveling or during regenerative control at ordinary speed, the reverse generated voltage generated by the motor has a low value, and there arises no problem even if the reverse generated voltage is applied to the fuel cell itself.
However, during traveling at high speed, that is, when the motor is rotating at high speed, high reverse generated voltage is applied to the fuel cell. Thus, when a value of such reverse generated voltage exceeds the cell voltage, the motor becomes unable to rotate, and therefore, when the motor should be rotated at higher speed, so-called “field weakening control” is performed as control to advance current phase, to thereby restrain generated voltage generated to be low.
If, however, a power control unit such as an invertor should be out of order and become unable to be controlled during such traveling at high speed, considerably high reverse generated voltage would be applied to the fuel cell, which is very dangerous.
On the other hand, although supposing such a trouble case, it is possible to use a motor, in which low generated voltage is generated, in order to make the generated voltage low, it is necessary to reduce a number of flux interlinkage of the stator winding. Therefore, it is necessary to use a permanent magnet having lower characteristic, or to reduce an amount of permanent magnet used or to reduce a number of turns of the stator winding, and therefore, there is a problem that the motor becomes a low-output, low-efficiency and low-performance motor, through which high input current flows (first problem).
On the other hand, in the above-described hybrid electric vehicle, when auxiliary output is caused by driving the motor during acceleration of the vehicle, the motor consumes a comparatively large amount of electrical energy of electric energy storing means of supplying electric power such as the battery. Therefore, when the motor is caused to generate auxiliary output in a state in which a small amount of electric energy is stored in the electric energy storing means during acceleration of the vehicle, during acceleration of the vehicle, the electric energy storing means is prone to be deteriorated.
Accordingly, in such a case, it is considered preferable to place the motor in an operation-stopped state (energization-interrupted state of motor) without generating auxiliary output by the motor.
Also, during cruising (during constant-speed traveling) of the hybrid electric vehicle, it is possible to travel the vehicle without a hitch only with the output of the engine concerned while fuel consumption of the engine is being made sufficiently low, and since consumption of electric energy of the electric energy storing means more than necessary is prone to deteriorate the electric energy storing means, the motor is generally caused to be in an operation-stopped state.
In the conventional hybrid electric vehicle, however, when the vehicle is traveling through the use of the engine output, the rotor of the motor is adapted to always rotate in synchronization with an output shaft of the engine. The rotor of the motor is directly coupled to the output shaft of the engine, or is connected to the engine output shaft through a gear or the like (see, for example, Japanese Patent Laid-Open Application Nos. 8-193531
Kadoya Naoyuki
Kondo Yasuhiro
Tagome Masaki
Aguirrechea J.
Mullins Burton S.
Ratner & Prestia
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